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Stalking to within 50 yards of your Cape buffalo and killing it properly is a challenge for your PH as well as for you, the hunter. Doing the job with your big bore rifle and iron sights adds to your memory trophy.
Ten old conventions from the Anglo-Boer War in the use of iron sights by the Boers which have a great deal of merit in the closer distances when shooting animals are presented at the end of this post. On top of those principles, experience and regular practice with open sights is needed before it should be used on any game - and particularly so on lion and Cape buffalo. Apart from the added skill It certainly is good preparation to know your own ability with open sights as a backup in case of a scope failure.
This blog explains a few basics from boresighting to aiming methods on game out to 100 metres. Physical measurements are from the sights on a SAKO Model L61 .375 Holland & Holland with a 600 (23.6") mm barrel. The principles will hold good for any rifle with a 23"-24" barrel.
Bore sighting
Refer to the diagramme in the figure below:
AB represents the height of the rear site top edge above the bore centre line.
CD represents the height of the front bead top radius above the bore centre line.
BD represents the distance between the rear and front sights.
In principle: to determine boresight distance in front of the muzzle the angle between the sight line and the bore line (angle AFB) must first be determined.
1. Angle AFB = angle ACE.
2. By the equation: tan of angle ACE = opposite side AE ÷ adjacent side CE.
3. The distance from the bore centre to the rear sight top horisontal edge (AB in the diagramme), minus the distance from the bore centre to the top radius of the front sight (CD in the diagramme) is the top value in the tan function.
3. The distance between the rear and front sights (BD) is the bottom value of this tan function.
4. Therefore: tan of angle ACE = AE ÷ CE.
5. Therefore: arc tan of (AE ÷ CE) = angle ACE, and also angle AFB.
To determine the bore sight distance from the muzzle:
Let "X" be the distance from the rear sight to ther boresight target.
6. Angle ACE = Angle AFB.
7. Therefore: tan of angle AFB = AB ÷ BF.
8. Therefore: tan of angle AFB = AB ÷ “X”
9. Therefore: “X” = AB ÷ tan of angle AFB.
10. Therefore boresight distance ahead of the muzzle (CF) = BF minus BD.
Example of SAKO .375 H&H, rear sight set for 300 gr round nose bullet on target at 100 metres
EC & BD = 463 mm
AB = 23 mm
CD = 21,8 mm
AE = 1,2 mm.
Angle ACE = Angle AFB
DF = (tan angle AFB) minus BD
So:
Let distance BDF = value “X”
tan function of angle ACE = AE ÷ CE
tan ACE = 1,2 ÷ 463
= 00026
Therefore Angle ACE = arc tan 0,0026
= 0,148 degrees
Angle ACE = Angle AFB
Therefore tan 0,148 = 23 ÷ “X”
Therefore 0.0026 = 23÷ “X”
Therefore “X” = 23 ÷ 0.0026 = BF
BF = 8.8 metres.
Therefore DF = 8.8 meters minus BD
DF = bore sight distance = 8.41 meters.
Aiming conventions with iron sights
A. How the bead is positioned in the rear sight “V” notch, and
B. How the bead is positioned on the animal to be shot.
1. The photos below show the convention for open sights aiming. The main principle with open sights is that the bead should never obscure the bullet impact point, therefore the top radius of the front sight bead is placed on the animal where the shooter wants his bullet to impact.
2. The convention for 100 metres is to have the bead top radius on the exact horisontal line of the top edge of the rear sight - fully “up” into the “V”.
3. For 50 metres the top radius of the bead should be halfway down into the “V”.
4. For Cape buffalo: The shooter must have a number of identical targets and practise over shooting sticks. Fire only two shots from 50 yards within six seconds - the follow-up shot offhand. Aiming must be exactly the same every time - with the bead top radius halfway down the “V” of the rear sight. The first and follow-up shots must be identified and marked as such on the target. A second identical target is then superimposed over the first one.
5. With at least a 10 minute break and a walk around the second string of two shots is fired with exactly the same aiming style as before and marked as first and second on both targets. A third identical target is then superimposed on the previous two and the exercise repeated and marked on all targets. Aiming must be exactly the same again for every shot – no compensation in aim must be made.
6. The first target paper with the 3-shots groups now shows the average position where the shooter will in all probability put that most importants first shot on his buffalo or lion. Should there be a distinct lateral error the shooter may wish to drift the front sight in the same direction as the error for the proper angular correction as will be shown in calculations in a next Blog post.
7. If there is a distinct vertical error the shooter should adjust the bead position in the notch of the “V” and always aim the top radius of the bead where he wants the bullet to impact.
8. Should the vertical fault be excessive the shooter may need to buy a replacement front sight with longer or shorter dimensions as is shown in the calculations in the nest blog post on this subject.
9. Any difference between the first-shots group and the group of follow-up off-hand shots will show the changed recoil dynamics between a rested shot and one from offhand. It is important for the shooter to shoot his rifle accurately off-hand at 30, 20 and 10 yards.
10. In the above example of the SAKO .375 H&H for a 100 metres shot the top radius of the front bead is protruding upwards into the open end of the “V” and held level with the top horisontal edge of the rear sight. The top radius of the bead is held where the shooter wants the bullet to impact. The Impact point is NEVER EVER covered with the bead.
It is strongly advised that the first time lion or Cape buffalo hunter – even if he will be using a telescope – will adopt the above practice regime for his preparation. Confidence based on real knowledge of the ability of the shooter-rifle-scope platform is a great start to a successful lion and / or Cape buffalo hunt.
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